Dovecot Settings Types


String settings are typically used with variable expansion to configure how something is logged. For example imap_logout_format:

imap_logout_format = in=%i out=%o

The # character and everything after it are comments. Extra spaces and tabs are ignored, so if you need to use these, put the value inside quotes. The quote character inside a quoted string is escaped with \":

key = "# char, \"quote\", and trailing whitespace  "

Unsigned integer

Unsigned integer is a number between 0..4294967295, although specific settings may have additional restrictions.


Boolean settings interpret any value as true, or false.

yes and no are the recommended values. However, y and 1 also work as yes. Whereas, only no will work as false.

All these are case-insensitive. Other values give errors.


The size value type is used in Dovecot configuration to define the amount of space taken by something, such as a file, cache or memory limit. The size value type is case insensitive. The following suffixes can be used to define size:

  • B = bytes

  • K = kilobytes

  • M = megabytes

  • G = gigabytes

  • T = terabytes

The values can optionally be followed by “I” or “IB”. For example K = KI = KIB. The size value type is base 2, meaning a kilobyte equals 1024 bytes.


The Time value is used in Dovecot configuration to define the amount of Time taken by something or for doing something, such as a sending or downloading file, processing, and more. The Time value supports using suffixes of any of the following words:

secs, seconds, mins, minutes, msecs, mseconds, millisecs, milliseconds, hours, days, weeks


So for example “d”, “da”, “day”, “days” all mean the same.

  • Time Interval:

    Combination of a positive integer number and a time unit. Available time units are mentioned above. To match messages from last week, you may specify

For example:

since 1w, since 1weeks or since 7days.

Millisecond Time

Same as Time, but support milliseconds precision.

IP Addresses

The IP can be IPv4 address like, IPv6 address without brackets like ::1, or with brackets like [::1]. The DNS name is looked up once during config parsing, e.g. If a /block is specified, then it’s a CIDR address like If a /block isn’t specified, then it defaults to all bits, i.e. /32 for IPv4 addresses and /128 for IPv6 addresses.


Special type of String setting. Conforms to Uniform Resource Locators (URL) (RFC 1738).